New band calculation method based on Nitrogen Loss Risk Index (NiLRI)
November 2022 release
The November 2022 release applies the Nitrogen Loss Risk Index (NiLRI) across all bands. NiLRI is the ratio of Nitrogen (N) fertiliser applied to crops and the cane yield expected (i.e. kg N / t cane). The pre-November 2022 version (version 3) employed this approach to assign sites into bands one to six. This release also includes sub-steps [link] to provide greater sensitivity of load reduction to changes in N application rates.
This approach simply allows representation of any farm management improvements that increase expected yield, and/or reduce N fertiliser rate for a given yield. The tool can now represent relatively small, estimated dissolved inorganic nitrogen (DIN) load reductions.
| Band | NiLRI/NUE |
|---|---|
| 1 | Less than 0.900 |
| 1.1 | 0.940 |
| 1.2 | 0.980 |
| 1.3 | 1.020 |
| 1.4 | 1.060 |
| 2 | 1.100 |
| 2.1 | 1.144 |
| 2.2 | 1.188 |
| 2.3 | 1.232 |
| 2.4 | 1.276 |
| 3 | 1.320 |
| 3.1 | 1.380 |
| 3.2 | 1.440 |
| 3.3 | 1.500 |
| 3.4 | 1.560 |
| 4 | 1.620 |
| 4.1 | 1.684 |
| 4.2 | 1.748 |
| 4.3 | 1.812 |
| 4.4 | 1.876 |
| 5 | 1.940 |
| 5.1 | 1.952 |
| 5.2 | 1.964 |
| 5.3 | 1.976 |
| 5.4 | 1.988 |
| 6 | Greater than 2.000 |
References
Peter J. Thorburn, Jody S. Biggs, Kevin McCosker, Adam Northey. 2022. Assessing water quality for cropping management practices: A new approach for dissolved inorganic nitrogen discharged to the Great Barrier Reef. Journal of Environmental Management. Volume 321. https://doi.org/10.1016/j.jenvman.2022.115932
